Dumbbell



FIG. 1 is a perspective view of a dumbbell showing my new design;

FIG. 2 is a front view thereof, wherein a rear view thereof is a mirror image of FIG. 2;

FIG. 3 is a left view thereof, wherein a right view thereof is a mirror image of FIG. 3;

FIG. 4 is a top view thereof, wherein a bottom view thereof is a mirror image of FIG. 4; and,

FIG. 5 is an enlarged cross sectional view thereof along lin 5—5 in FIG. 2. 

The ornamental design for a dumbbell, as shown and described. 